1. Field
The present invention relates to a drive mechanism that converts a force supplied from an operator or other means along an adjustable curve path into rotary motion. More particularly, the present invention relates to an adjustable drive mechanism configured for an operator driven or motor driven exercise apparatus such as a stationary bicycle, recumbent stationary bicycle, cross trainer or other devices.
2. State of the Art
The benefits of regular exercise to improve overall health, appearance and longevity are well documented in the literature. For exercise enthusiasts, the search continues for safe apparatus that provides exercise for maximum benefit in minimum time with less boredom.
Exercise bikes currently use simple cranks to guide the feet along a circular path while receiving operator force to rotate a flywheel. Several attempts have been made to guide the feet along an elliptical path while seated for exercise such as Eschenbach in U.S. Pat. No. 5,836,855 and Maresh in U.S. Pat. No. 5,938,570. Knudsen in U.S. Pat. No. 5,433,680 shows an elliptical path generating mechanism with pedals having only one pivot allowing the pedal to rotate unconstrained about the pivot as in a bicycle crank. Marchou in U.S. Pat. No. 2,088,332 shows a gear pair configured to receive force from a piston. Stiller et al. in U.S. Pat. No. 5,419,572 shows a pair of gear stacks used to guide foot pedals along an elliptical path for a bicycle. Ticer et al. in U.S. Pat. No. 5,261,294 shows an adjustable elliptical crank using gears applicable for exercise.
Recently, a new category of exercise equipment has appeared on the commercial market called elliptical cross trainers. These cross trainers guide the feet along a generally elliptical shaped curves to simulate the motions of jogging and climbing. Several commercial cross trainers are now offered with elliptical foot movement that can be changed when desired by an operator.
Rodgers in U.S. Pat. No. 5,743,834 shows an elliptical cross trainer having an adjustable crank where a motor attached to a moving crank arm can change crank length using gears and screw threads. Stearns et al. in U.S. Pat. No. 6,027,431 shows an elliptical cross trainer having an adjustable crank where gear pairs and a spiral slot operated by a stationary motor change the length of a crank arm. Other variations of an adjustable crank are shown in Stearns et al. in U.S. Pat. No. 6,338,698 and U.S. Pat. application No. 2002/0198084 A1 using various linkage and slotted discs.
There is a need for a drive mechanism to guide a pedal, foot support, connector link or handle along an adjustable curve that is easier to fabricate than the prior art. There is a further need for an adjustable drive mechanism that can be incorporated in an exercise apparatus or other device where the drive pivot such as a pedal follows an adjustable curve during operation of the exercise apparatus. There is a further need for a drive mechanism that changes radius on a periodic basis.
It is one objective of this invention to provide an adjustable drive that allows variable pedal movements. Another objective of this invention is to integrate the adjustable drive into several exercise apparatus. Yet another object of this invention is to provide an indirect application of the adjustable drive to adjust pedal path curves for exercise apparatus.